modiho

    var Q = require('q');

    function getUserFriends(userName) {
      return Q.nfcall(db.users.findOne, {name:userName});
    }

    function foundOne(user) {
      return Q.nfcall(db.friends.find, {userId:user.id});
    }

    function foundFriends(friends) { ... }

    getUserFriends.then(foundOne).then(foundFriends);